Actor Leonardo DiCaprio has been challenged by a leading US memorabilia dealer to bid for a photograph of himself with Nelson Mandela. The actor is considering to take a legal action to seize the photograph. Gary Zimet, the boss of memorabilia store Moments in Time, is selling a picture of the "Titanic" star with the late civil rights icon, taken in 2007, for $25,000, reports contactmusic.com. The photograph also has a handwritten tribute that states: "To Leo DiCaprio, Best Wishes, Mandela, 4-8-07". The star is reportedly unhappy about the sale. A newspaper claims that DiCaprio believes the photograph is rightfully his and he is consulting lawyers to acquire it. (Source: IANS)